106 BULLETIN 903, U. S. DEPARTMENT OF AGRICULTURE. 
the end of the third week in August. The condition of the soil was 
about the same in both years, moisture being somewhat higher than 
usual because of extra heavy precipitation each spring. The reten- 
tion of moisture near the soil surface tends to produce many fleshy 
rootlets, and these in turn produce abundant nymphs and wandering 
larva?. Thus a wet spring results in the early production of migrants 
and wandering larvae. 
A number of laboratory observations were made on the wandering 
larvae. From these it appeared that the insects were capable of 
walking as much as 14 feet on a smooth surface, provided a strong 
light attraction was present. On fine soil their appendages became 
clogged very soon, and prevented further locomotion, but on hard 
surfaces, they progressed successfully. On warm surfaces they easily 
became " baked " to death, and in fact always lived the longest when 
least exposed to the sun. as the heating of the surface soil killed the 
aphids. Larvae easily passed over wet sand and were able to make 
headway on dry sand, but could not penetrate sand. It was found 
that the larvae could remain alive at least for three days, wandering 
around partly upon the soil and partly in cracks in the soil in a 
flowerpot subjected to an average amount of direct sunlight. 
During the summer and autumn of 1911 a number of young rooted 
vines were planted in 9-inch pots, and these were inoculated during 
May and June by burying phylloxerated roots around the stalk or by 
transferring eggs to the larger roots. These vines included viniferae, 
American nonresistants, and resistants. On the top of these pots 
and resting on the earth were fitted tightly circular pieces of wood 
with a hole in the center, through which passed the stalk of the 
vine. The whole aerial portion of the vine was inclosed in a muslin 
cage. This construction was designed to compel phylloxerae ascend- 
ing to the soil surface to make their way through the hole around 
the stalk; and having done so, they would be unable to escape by 
reason of the white muslin cage and would soon die. In October 
and November these cages were examined, and in some of them 
small numbers of dead wanderers were found, in others none, and 
in still others very large numbers. Those containing dead wan- 
derers in abundance were the ones in which the vines had been fer- 
tilized with chemical fertilizers, and there was also a corresponding 
abundance of winged migrants from such vines. The action of the 
fertilizers produced many migrants and many wanderers and in- 
vigorated the vines, yet in all cases a large root infestation by wing- 
less forms persisted through the winter following. In the cages 
above mentioned fertilizers, in liquid form, were applied periodically 
during the summer. In 1915 a similar series of vines were fertilized 
with solid fertilizers at the time of planting in early spring, and 
